The proliferation of inexpensive cameras and image signal processing has resulted in many new systems that replace normal computerized input systems with cameras. Television remote controls, game controllers, and computer keyboards and mice have been replaced in some cases with a set of cameras and microphones in televisions, gaming consoles, and computers. For some systems, the camera is attached to the main system and, in other cases, the camera is a separate part that can be mounted in a place that provides good visibility of possible users. The cameras observe hand and body motions of the user and interpret these motions as commands.
A gesture or body movement recognition system presents many difficulties. It is difficult for a set of cameras to view, analyze and interpret a gesture as quickly as it is to receive a button press. There are difficulties with determining whether a user is gesturing to the camera or to another person. There are difficulties with recognizing and distinguishing a hand in a crowded space with poor lighting. There are also difficulties with distinguishing different parts of a hand. Further difficulties are associated with smoothing the motion of the tracked point on a hand and with the differences between a tracked image of a hand and the screen resolution.
Most gesture and body control systems respond to side-to-side and up and down movement. The range of gestures is therefore only two-dimensional. Recently multiple camera systems allow depth or distance from the camera to be determined. This opens up new avenues for gesture and body control because the camera can determine movement also in the third dimension. For the user, this movement is front to back or towards and away movement.